At slow shutter speeds, a blinking orange icon is displayed on the lower left portion of the G1X display. This icon is to warn you that shutter speeds may be too slow and that a tripod is needed. Once you know what it is, you realize that the icon is a shaky camera. So when does the warning appear?
I set up a simple experience in which focal length, shutter speed, aperture, Image Stabilization and ISO were varied and noted the fastest shutter speed for which the shake icon remained turned on. As suspected, ISO and aperture were quickly eliminated as having an effect. The shake icon activation logic is a simple function of focal length and shutter speed; however, Image Stabilization (IS) is definitely a factor.
There is an old rule-of-thumb of 35mm photography that says the slowest shutter speed that should be hand-held is 1/focal length. For example, when shooting a 100mm lens, a tripod should be used if the shutter speed is slower than 1/100 second. This “rule” was developed before the introduction of Image Stabilization. Of course, it is not a law of nature – only a rough guide for pointing to the need for a tripod. A little too much coffee and a tripod is always needed!
In very rough terms, the old 1/focal length rule applies to the G1X when IS is turned OFF. With IS turned ON, the shutter speed can be 3x slower before the shake icon appears. All these “calculations” (if indeed they are done) are then rounded off. Strangely (to me), the effects of digital zoom are not a factor. Also, the IS effect on shake icon activation is identical whether IS is for single shot or continuous. “Power IS” does not seem to matter.
I can remember the simple rule of thumb but here’s a chart of the data.